Funding is requested to renew a training program that aims to train the next generation of behavioral scientists with expertise in the prevention of HIV and related co-morbidities (i.e. TB, viral hepatitis and STls) among substance using populations. Our program builds upon the joint doctoral programs (JDP) in public health and clinical psychology offered through a longstanding partnership between the University of California San Diego (UCSD) School of Medicine and the San Diego State University (SDSU) Graduate School of Public Health and School of Social Work. In this renewal, a new JDP beginning in 2013 on Social Sciences Research in Substance Abuse will further enhance our applicant pool, and our extended focus beyond HIV co-infections to consider co-morbidities reflects additional breadth. Our objectives are: 1) To provide opportunities for interdisciplinary research training experiences for predoctoral students and postdoctoral fellows in epidemiology, health behavior and psychology who wish to focus on prevention research at the intersection between substance abuse and HIV and related co-morbidities; 2) To offer students hands-on experience in the prevention of HIV and related co-morbidities in international settings; 3) To recruit and train researchers from diverse academic backgrounds and under-represented minority (URM) populations with state-of-the-art skills to address challenges in substance use and HIV prevention research; and 4) To train individuals in the responsible conduct of research with human subjects, especially in international and cross-cultural settings. After 4 years of support, our program has supported 16 trainees. Of the 6 postdoctoral fellows and 3 predoctoral trainees who completed training, all remain active in the field; 4 completed Fellows are now Assistant Professors. Three Fellows successfully competed for K01s; one predoctoral trainee received an R36 dissertation grant and a second was granted a Diversity Supplement. We have supported 5 URM, of whom 3 already completed training. Collectively, trainees published 59 manuscripts during their training. We request support for 3 predoctoral and 3 postdoctoral trainees, mentored by 17 Core Faculty. Depending on their level of training, mentees are required to complete courses in substance abuse and infectious diseases, instruction in responsible conduct of research, quarterly cultural sensitivity training workshops, monthly 'Work In Progress' seminars and a grant-writing seminar. Our active research programs in nearby Mexico and 8 other countries create the opportunity for unique, hands-on international training experiences and an infrastructure for trainees to develop into independent investigators.